Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Brucella melitensis [ICD11:
XN7ZW 
]
The structure was elucidated in this paperNCBI PubMed ID: 3442684Journal NLM ID: 0370623Publisher: American Chemical Society
Institutions: Division of Biological Science, National Research Council of Canada, Ottawa
The Brucella M antigen from the species type strain Brucella melitensis 16M has been identified as a component of the cell wall lipopolysaccharide (LPS). O polysaccharide liberated from this LPS by mild acid hydrolysis exhibited M activity in serological tests and was shown to be a homopolymer of 4-formamido-4,6-dideoxy-α-D-mannopyranosyl residues arranged in an oligosaccharide repeating unit as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the native lipopolysaccharide. Structural analysis of the O polysaccharide by NMR methods was difficult due to apparent microheterogeneity of the repeating unit, which was in fact caused by the presence of rotational isomers of the N-formyl moiety. This problem was resolved by chemical modification of the polysaccharide to its amino and N-acetyl derivatives, the 500-MHz 1H and 125-MHz 13C NMR spectra of which could be analyzed in terms of a unique structure through application of pH-dependent beta-shifts and two-dimensional techniques that included COSY, relayed COSY, and NOESY experiments together with heteronuclear C/H shift correlation spectroscopy. On the basis of these experiments and supported by methylation and periodate oxidation data, the structure of the M polysaccharide was determined as a linear polymer of unbranched pentasaccharide repeating units consisting of four 1,2-linked and one 1,3-linked 4,6-dideoxy-4-formamido-α-D-mannopyranosyl residues. The marked structural similarity of the M antigen and the A antigen, which is known to be a 1,2-linked homopolysaccharide of 4,6-dideoxy-4-formamido-α-D-mannopyranosyl units, accounts for cross-serological reactions of the two and the long-standing confusion surrounding the nature of their antigenic determinants. Structural and serological considerations in conjuction with the sodium dodecyl sulfate banding pattern of Brucella A LPS suggest that its biosynthesis differs appreciably from that of the M antigen, which appears to be synthesized by regulated assembly of preformed oligosaccharide repeating units. Temperature, lysogenic phage may be responsible for such biosynthetic and structural variations.
Structure type: polymer chemical repeating unit
Trivial name: M antigen
Compound class: O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_130647,IEDB_131172,IEDB_134279,IEDB_134280,IEDB_134281,IEDB_1397515,IEDB_2116320,IEDB_434544,IEDB_434545,IEDB_434546
Methods: 13C NMR, 1H NMR
Related record ID(s): 108579, 130218, 139863, 148075
NCBI Taxonomy refs (TaxIDs): 29459Reference(s) to other database(s): GTC:G53253RW, GlycomeDB:
3021
Show glycosyltransferases
There is only one chemically distinct structure:
Found 
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